During the past few decades there has been tremendous increase in demand for performing various optical processing/operations using a single device. Waveguides play an important role in this field. Waveguides have gained importance since they are used for communication in an optical network.
Typically, waveguides are manufactured by a number of ways. One of the most important techniques is using the femto-second laser in which straight waveguides of separation in the order of 5-30 μm and depth of few micro meters are prepared. These waveguides support self-focused beams denoted as discrete solitons, which is an envelope of the field intensities that extends over a minimum of five waveguides. The unique features of the solitons, particularly their dispersionless propagation, have encouraged many previous proposals to use them for the so-called all-optical operations.
One such device that uses solitons to perform the switching operations is a “blocker soliton”. The blocker soliton is a high-intensity fixed power soliton that serves as a reflector of incoming signal. This device allows only signals of a certain velocity to pass, while reflecting others. This device however can only be used as switch. Further, the blocker soliton is not confined, which in turn leads to ruining the functionality of the device. The use of waveguides proves to be advantageous when solitons are considered for data transfer in order to confine the solitons for providing clean output and thereby resulting in robust functionality with almost no background radiation.
It is known that when the separation between waveguides is modulated, the associated coupling coefficient, which is proportional to the probability to tunnel from one waveguide to the next one, is also modulated according to an exponential law. For solitons propagating across the waveguides, this modulation is an effective potential. Designing the separations between the waveguides in a certain (pre-calculated) manner results in a special type of potential known as reflectionless potential. Scattering solitons off reflectionless potentials is characterized by clean particle-like scattering with almost no background radiation.
Now-a-days the use of optical fibers has become the new generation for data transfer. Such use of optical fibers has exceeded by orders of magnitude the speed and band width of the electronic means. However, these gains are downgraded by the use of electronic-based data processing at the user's end. Such downgrading resulted in the demand for all-optical data processing in order to be compatible with the high bit-rate optical data transfer. Hence, there arises a need for a practical solution that enables all-optical operations with a simple device made of waveguide arrays.
While all the above is known in the literature as theoretical or experimental facts, there is a need for a highly useful device which can act as a single device for performing multiple electronic operations of devices such as logic gates, diodes, switches and filters. Such a device shall increase the efficiency of an optical communication network in which it may be employed. Further, there is a constant need for improving the processing speed in the communication network and obtaining a clean output.